From cd97f39b7cdf1c8a9c9f52865eec795b7f0c811d Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Tue, 24 Feb 2009 19:19:49 +0100 Subject: [PATCH] i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT The unit in which user-space can set the bus timeout value is jiffies for historical reasons (back when HZ was always 100.) This is however not good because user-space doesn't know how long a jiffy lasts. The timeout value should instead be set in a fixed time unit. Given the original value of HZ, this unit should be 10 ms, for compatibility. Signed-off-by: Jean Delvare Acked-by: Wolfram Sang --- drivers/i2c/i2c-dev.c | 6 +++++- include/linux/i2c-dev.h | 2 +- include/linux/i2c.h | 2 +- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index c171988..7e13d2d 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -35,6 +35,7 @@ #include #include #include +#include #include static struct i2c_driver i2cdev_driver; @@ -422,7 +423,10 @@ static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) client->adapter->retries = arg; break; case I2C_TIMEOUT: - client->adapter->timeout = arg; + /* For historical reasons, user-space sets the timeout + * value in units of 10 ms. + */ + client->adapter->timeout = msecs_to_jiffies(arg * 10); break; default: /* NOTE: returning a fault code here could cause trouble diff --git a/include/linux/i2c-dev.h b/include/linux/i2c-dev.h index 311315b..fd53bfd 100644 --- a/include/linux/i2c-dev.h +++ b/include/linux/i2c-dev.h @@ -33,7 +33,7 @@ */ #define I2C_RETRIES 0x0701 /* number of times a device address should be polled when not acknowledging */ -#define I2C_TIMEOUT 0x0702 /* set timeout in jiffies - call with int */ +#define I2C_TIMEOUT 0x0702 /* set timeout in units of 10 ms */ /* NOTE: Slave address is 7 or 10 bits, but 10-bit addresses * are NOT supported! (due to code brokenness) diff --git a/include/linux/i2c.h b/include/linux/i2c.h index fcfbfea..c86c3b0 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -361,7 +361,7 @@ struct i2c_adapter { struct mutex bus_lock; struct mutex clist_lock; - int timeout; + int timeout; /* in jiffies */ int retries; struct device dev; /* the adapter device */ -- 2.7.4